A golf putter should provide "feel" to the golfer. That is, it should provide a feeling of precise control over the ball. A high vibration, if felt in the grip, or even heard, tends to destroy the feeling and psychology of control. The low frequencies give the solid "feel" to the putter and gives the golfer a reference, both as to feel and sound, to be sought in subsequent putts. Therefore, a putter should carry low frequencies to the grip, but not high frequencies. It is also desirable for the low frequencies but not the high frequencies to be heard, when the ball is hit correctly.
Each golf club has a "sweet spot" on the face of the head. The "sweet spot" is the point on the face of the head, in which the golf ball is best struck and which moves the ball in a straight direction. The "sweet spot" is located on the face of the head along a line passing through the center of inertia of the head. When a ball is struck at the "sweet spot", there is a solid "feel" to the strike and little or no torque is imparted to the club. Golfers test for the "sweet spot" on a putter by holding the face of the putter horizontally and dropping the ball on the face. They then listen for a "chuck", or low frequency, sound rather than a "ping", or high frequency, sound. The "chuck" sound denotes the "sweet spot". The "sweet spot" area is a general area around the "sweet spot" which, if the golfer hits within the "sweet spot" area, provides an acceptable golf shot. The "sweet spot area" may be approximately 2.5" in length, on, say, a face which is approximately 4 inches long. The best part of the "sweet spot" area, to hit the ball, is approximately one third the diameter of a golf ball in width, or 0.56", although striking within a width of 0.8" around the "sweet spot", will likely be quite an acceptable hit.
In putting, it is intended that the ball be struck on the "sweet spot" on the face of the putter, which is generally at or near the central area of the face. However, golfers do not always strike the ball within the "sweet spot" area of the club head and will sometimes, because of an inaccurate stroke, hit the ball outside the "sweet spot" area. If a putter is properly designed, as in the present invention, it can prevent disastrous results from an inaccurate stroke. In one of the embodiments, the putter provides some correction for inaccuracies of stroke.
Also, it is desirable on the putting green to give a gall backspin and lift. Various putters in the past have included angular or curved surfaces to provide overspin to the ball to help it roll forward in a straight line. U.S. Pat. No. 4,162,074 to William B. Thompson shows a bulge, or a convex surface, claimed to impart topspin, or overspin, to a golf ball.